1. Field of the Invention
This invention relates to pipe joint apparatus and more particularly relates to retainer glands for holding pipe joints together.
2. History of the Prior Art
The use of segmented or split pipe joint retainer glands is well known. In addition to being used on pipe joints, such devices also have been used on valves, fittings, hydrants, and other pipe connections where it is necessary to secure together or restrain two members which tend to separate in response to fluid pressure from within. Typical uses for such pipes structure are sewers and for water distribution. Some prior art devices are shown in U.S. Pat. Nos. 3,627,357 and 3,726,549. Another apparatus for connecting pipes together is illustrated in U.S. Pat. No. 2,821,416. Both U.S. Pat. Nos. 3,726,549 and 2,821,416, show segmented pipe retainer glands which are secured together around a pipe section by ears or lugs formed on and extending radially outwardly from adjacent ends of the gland segments. Such segmented glands have been used on small pipe diameters. In the past, the strength requirements for large diameter pipe lines has limited the segmented gland use to very low pressures. Most such prior art designs utilize a simple bolt connection between the lugs on the ends of the gland segments. Such arrangements allows the segments to bend and separate at the joints between the segments, thereby reducing the grip on the pipe surface to the extent that the retainer glands slip and the joints separate. The stress in the conventional prior art devices between the clamping ears and the circular segments of a segmented gland are along planes which are generally axial and circumferential. The prior art devices having segments held together by bolted end lugs are limited in size. It has been found that those as large as 12 inches in diameter will not function satisfactorily. In contrast, segmented glands made in accordance with the present invention can range in size from 4 inches to 48 inches in diameter.